Congress should censure Nunes. Just like McCarthy.

The last time a member of Congress made a reckless and baseless attack on a revered pillar of America's security, it did not end well for him. Sen. Joseph McCarthy got away with smearing the State Department, which has never received the popular esteem it deserves, but when he took on the U.S. Army, accusing it of harboring a subversive dentist (really!), he went too far.

During the 1954 Army-McCarthy hearings, Army counsel Joseph Welch delivered his famous rebuke — "Have you no sense of decency, sir? At long last, have you left no sense of decency? " — and that was it. McCarthy was censured by the Senate and stripped of his committee chairmanship.

Let us stipulate that Devin Nunes (R-Calif.), chairman of the House Intelligence Committee, is not exactly the second coming of "Tail Gunner Joe ": that dubious honor more properly belongs to the conspirator in chief, President Trump. But for his deceptive, demoralizing and dangerous assault on the FBI — an institution that, like the Army, is dedicated to defending America — Nunes, too, deserves to be censured by his colleagues and stripped of his chairmanship.

Nunes began his reign of error nearly a year ago. Last March 22, he breathlessly announced he had uncovered evidence that the intelligence community — presumably the FBI or the National Security Agency — had improperly monitored and unmasked "Trump transition team members." Then he rushed off to the White House to brief the president on his "findings."

It was all a sham. Nunes was simply covering for Trump after the president claimed that President Barack "Obama had my 'wires tapped' in Trump Tower." When no evidence of wiretapping emerged, Nunes tried to morph the accusation into a claim that Obama national security adviser Susan E. Rice illegally "unmasked" Trump aides in surveillance transcripts. This, too, was false. Trump's own national security adviser, H.R. McMaster, concluded that Rice "did nothing wrong."

The discredited Nunes found himself the subject of an Ethics Committee investigation over whether he had improperly revealed classified information. He had to recuse himself from the Russia probe, but this did not stop him from spinning conspiracy theories about FBI agent Peter Strzok, who was removed from special counsel Robert S. Mueller III's investigation over texts critical of Trump and other public figures.

On Dec. 7, the House Ethics Committee closed its investigation of Nunes, even though, according to the Atlantic, "the committee was never able to obtain or review the classified information at the heart of the inquiry." Back on the Russia case, Nunes directed his staff to prepare a memorandum alleging the FBI had falsified a surveillance warrant — without bothering to read the underlying intelligence. The FBI and Justice Department objected to the release of this one-sided document, which, they warned, risked compromising sensitive intelligence.

Nunes didn't care. He and other Republicans, joined by Russian bots and right-wing talking heads, spent weeks lobbying to #ReleasetheMemo . Nunes convinced fellow Republicans on the House Intelligence Committee to vote for the memo's release, while conveniently keeping secret a Democratic rebuttal. Trump declassified the Nunes memo last week, because he, too, is eager to discredit the FBI at any cost.

Nunes claimed to have found "serious violations of the public trust," showing that "officials in critical institutions are abusing their authority for political purposes." Trump bizarrely tweeted, "This memo totally vindicates 'Trump' in probe." (The quote marks would have made more sense around "vindicates.") Trump, who called Nunes a "Great American Hero," may yet use Nunes's bogus research as an excuse to oust Deputy Attorney General Rod J. Rosenstein or even Mueller, after having already purged FBI Director James B. Comey and Deputy Director Andrew McCabe.

In reality, the Nunes memo was, as widely noted, a dud. It did not uncover any wrongdoing by the FBI, much less by Mueller. Its central claim — that the FBI and Justice Department obtained a surveillance warrant for Trump campaign adviser Carter Page based on ex-spy Christopher Steele's work, while hiding Steele's Democratic Party funding — is false. The Steele dossier was only one piece of evidence among many, and the Justice Department did reveal that Steele was paid by an anti-Trump political entity, even if it did not name the Democratic National Committee.

Nunes undercut his own case by confirming the FBI began investigating the Trump campaign not because of the Steele dossier, but because of information from foreign-policy adviser George Papadopoulos. As if he didn't already look foolish enough, Nunes said Page should never have been a "target of the FBI," right before Time magazine reported that Page boasted in 2013 of being an "informal adviser" to the Kremlin.

Like Trump, Nunes would be more dangerous if he were more competent. But just as Trump must be held accountable for his attempts to obstruct justice even if they don't succeed, so, too, Nunes must be held accountable for his misuse of a congressional committee to pursue a partisan vendetta against the nation's premier law-enforcement agency.

It is up to House leaders — that means you, Speaker Paul D. Ryan (R-Wis.) — to stop Nunes before he smears again. (Nunes already has the State Department in his sights.) History does not look kindly on the lawmakers who were too cowardly to confront McCarthy. It will be even harsher on those who refuse to confront McCarthy's latter-day mini-me, who is not nearly so fearsome.